Device for feeding a continuous web



Sept. 22, 1953 Filed June' 16, 1949 A. O. RUSSELL ETAL DEVICE FOR FEEDING A CONTINUOUS WEB a, I 53m. INVENTORS. 53K ARTHUR o. RussEL MICHAEL GRAVATT JONES (T1 r WILL/AM M. WATTJ 3 .ss B wfi 7 Sheets-Sheet 1 A rggmv: X

Sept. 22, 1953 A. o. RUSSELL ET AL DEVICE FOR FEEDING A CONTINUOUS WEB Filed June 16, 1949 7 Sheets-Sheet 2 INVENTORS. AR THUR O. RUJJEL MICHAEL GRAVA TT JONES WILLIAM M WAT r6 BY 1 A TTORNEX Sept. 22, 1953 A. o. RUSSELL ETAL 'DEVICE FOR FEEDING A CONTINUOUS WEB 7 Sheets-Sheet 3 Filed June 16, 1949 I INVENTORS. ARTHUR O. RUGJJEL MICHAEL GRAVATT JONES v Arromvzx Sept. 22, 1953 A. o. RUSSELL ET AL DEVICE FOR FEEDING A CONTINUOUS WEB 7 Sheets-Sheet 4 Filed June 16, 1949 1. .1. s, $9 1 llll ilk INVENTORS ARTHUR o. RUSSEL MICHAEL GRAVATT JONES WILLIAM M WA TTS ATTORNEY- A. o. RUSSELL ETAL DEVICE FOR FEEDING A CONTINUOUS WEB Sept. 22, 1953 7 Sheets-Sheet 5 Filed June 16, 1949 INVENTORJ. ARTHUR O. RU-SS EL MICHAEL GRAVATT JONES WILL IA M M. WA TT\S ATTORNEY Sept. 22, 1953 A. o. RUSSELL ETAL 2,653,023

DEVICE FOR FEEDING A CONTINUOUS was 7 Shets-Sheet 6 Filed June 16, 1949 INVENTORS. ARTHUR 0. Russ EL MICHAEL GRAVATT dONE6 WILLIAM M WATTS ATTORNEY i Sept. 22, 1953 A. o. RUSSELL ETAL 2,653,023

DEVICE FOR FEEDING A CONTINUGUS WEB Filed June 16, 1949 v Sheets-Sheet 7 AAAAA I INVENTORS, ARTHUR o. Russm.

MICHAEL GRAVATT JONEGS WILLIAM M. WATT$ Patented Sept. 22, 1953 UNITED STATES PTENT OFFICE DEVICE FOR FEEDING A CONTINUOUS WEB Application June 16, 1949, Serial No. 99,464

'7 Claims. (01. 271-) This invention relates to a device for intermittently feeding a web or band to a cutting position, setting the feed mechanism to overfeed slightly, and occasionally overcorrecting the feed by a light-responsive device such as a photocell to incapacitate the feeding means a predetermined distance ahead of the end of its forward feeding stroke when a predetermined index on the web or band passes under the photocell, repeatedly cutting the band and stacking the pieces to facilitate acking.

In such intermittent feeding systems, there is a permissible latitude or tolerance with respect to the position of cutting and it is a primary object of the present invention to speed up such machines by making it unnecessary for the lightresponsive system to control every feeding stroke of the feeding mechanism. A further object of the invention is to provide for the automatic stacking of the cut sections in superposition to facilitate the packaging thereof. A further ob ject is to provide such feeding systems with a stroke-adjusting means that can be adjusted while the machine is in operation. A further object is to provide an adjusting means of such construction that the entire variation in length is effected without changing the forward point of the feeding stroke. Other objects of the invention will be apparent from the drawing and the description thereof hereinafter.

Figure 1 is a side elevation of the machine and its drivin connections,

Figure 2a is an elevation in cross-section of the supply end of the mechanism with the driving connections removed, taken on line AA of Figure 3a,

Figure 2b is a similar view of the discharge end of the mechanism taken on line A A of Figure 313,

Figure 3a is a plan View of the supply end of the mechanism,

Figure 3b is a plan view of the discharge endof the mechanism,

Figure a is a section on line BB of Figure 2a, Figure 5 is a section on line C-C of Figure 3?), Figure 6 is a section on line 13-43 of Figure 222, Figure 7 is a section on line EE; of Figure 2 0, Figure 8 is an end View of the cam and switch control,

Figure 9 is a diagrammatic view of the electrical connections,

Figure if) is a transve to section of the feed mechanism taken on line FF of Figure 3b, and

Figure ii illustrates a stroke-adjusting mechanism.

As shown in Figure 1, a supporting framework comprises corner posts 3 and i, a horizontal top frame 5 and a lower supporting frame 5. At one end of the top frame 5 a pair of brackets l are carried and have bearing grooves 8 adapted to receive a shaft 9 upon which a reel or roll it of a web or band material H is rotatably mounted. The other end of the top frame 5 carries a bed frame [2 to the opposite sides of which are secured a pair of upright side plates i3. The two side plates l3 support the operating connections of the feeding and cutting mechanism and cooperate with the upright end plate I4 to support the stacking mechanism P.

A motor I 5, drives a variable speed gearing l6 and a gear reduction box ll through suitable connections such as belts i8 and I9 respectively which cooperate with pulleys 20, 2i, 22 and 23. Sprockets and chains may be substituted if desired. The sprocket 2d driven by the gear box i l drives a crank-shaft 25 through the chain 26 and a sprocket 2?. The shaft 25 drives shafts 23 and 29 respectively through the chains 36 and 3! and sprockets 32, 33, 3d and 35 (see also Figure 3a).

Referring more particularly to Figures 2a and 2b and 3a and 3b, the band or web H proceeds from the reel it) about a roll 36 rotatably mounted eccentrically on a disc 37 secured to shaft 23 for rotation therewith. The web or band then passes upwardly between guides Hi: and over the roll 33 fixedly mounted on a cross-shaft 39 rotatable in hearings in the opposite upright frame mercy bers l3. From the roll the web or band passes under a clam generally indicated at J in Figures 2a, 3a and i, under a tensioning rider indicated at K, under a light-detecting system generally indicated at L, then (see Figures 2?) and 312) into the intermittent feeding mechanism generally indicated at M, then between the jaws at N, through the cutter at O, and into the stacker generally indicated at P.

Intermittent feed The intermittent feeding mechanism generally indicated at M (see Figures 222, 3b, 5 and 10) comprises a reciprocable bottom plate ii] having a plurality of upwardly projecting parallel ribs ii extending lengthwise of the direction of feed. Spaced rails 42 having opposed grooves 63 serve as guides for the edges of the plate is and a depending lug i t is connected to a link by means of a yoke &8. The other end of the link to is secured to a pin ii (Figure 2a) by a fitting it rotatable on the pin. The other end of the pin is adjustably secured in a slot 48 of the lever i 1 is fixedly secured to the shaft The designed to provide a fixed forward :csition of the feeding mechanism. regardless of stroke length. Shifting the connection of rod 55 in the slot changes the stroke by changing the return position of the mechanism. This shaft is rotated by a lever 52 which is pivotally connected to the connecting rod 53 secured to a crank 5 eccentric with respect to the crankshaft 25.

A plurality of parallel guide bars 55 are disposed between the ribs 4| and are secured to a horizontal cross piece 56 at one end and a cross rod 57 at the other. These guiding bars 55 form a bed for the web or band to pass over as it is drawn by the feeding mechanism. The guide bars 55 and the ribs 4| are shown with their upper surfaces disposed in a plane that is a continuation of the top surface of a plate but their upper surfaces may be slightly above or below this level, and/or the upper surfaces of ribs 4! may be slightly higher than those of bars in which event it may be desirable to provide longitudinal grooves in the upper surface of ribs M to reduce the friction on the return stroke. The plate 58 at each end has depending yokes 55 and 60 fitting over the cross-shafts 51 and 6! respectively. Four hollow posts 62 extend above the plate 40 and are secured in place by suitable screws 63 which engage threaded bores in the plate 40. Cross-straps 64 are carried by the posts 62 and held in place by the screws 63. An upper plate 65 is supported under and by the straps 64.

A plurality of depending members 66 (Fig. 10) are pivotally supported by cross-shafts ill through their upper ends. As shown, there are three such gripping members 65. When the upper surfaces of ribs 4| and bars 55 are in the same plane, it is desirable, as shown, to notch the lower end of the gripping members to provide a number of fingers 61 disposed above and in alignment with the ribs M of the lower feed plate 40. At each side of the gripping members a side link 68 connects the members 56 to a lever 09 pivotally mounted at 10a on the upper plate 55. The levers 59 are secured to a cross rod H at their upper ends and this rod has an upwardly extending armature 12 of magnetic material. Normally, the fingers 61 of the comb-like members engage, by virtue of gravity, the upper surface of the web or band therebeneath and since the upper plate 65 is secured to the lower feeding plate 40 and must move with it, the web is gripped between the fingers 51 and the ribs 4! during the forward stroke of the feeding device.

The stroke of the feed plate 40 can be changed by adjustment of the position of the pin 4! in the slot 49 of link 50 and this stroke is set to give a slight overfeed, say up to .005 to .01 inch.

Stroke correction Near the end of the forward feeding stroke, which is the position shown in the figures, the armature 12 passes between the depending poles E3 of an electromagnet comprising a coil 14. The magnet is carried on the fixed frame of the machine by a bracket 14a along which the magnet is adiustable so that its position relative to the foremost position of armature 12 can be varied to provide the amount of stroke correction desired. Energization of the magnet is effected when an index on the band or a change in the light-reflective properties of the band passes into 4 the field of the photocell 15. This photocell may be housed in a casing 16 having a restricted opening I! just above the traveling Web and optionally a lens system Tia. The casing 16 may support a light source 18, the casing of which has a light-directing opening 19 and optionally a condensing lens system 19a pointing toward the part of the web directly beneath the opening 11.

The crank-shaft 25 carries at one end two cams and 81 (see Figures 3a, 8, and 9) against which spring contact arms 82 and 83 bear. The actual engagement between the arms 82 and 03 and the cams 80 and 8| may be made by followers 85 The photocell i5 is connected by suitable leads 86 to an amplifier 8'! which may be housed in the casing 16 and may have any conventional construction. The amplifier is connected by the loads 88 and 88a to an electronic system comprising a thyratron tube 89. The switch controlled by the cam 85 is in series with the grid circuit so that when the switch 90 is open, the photocell cannot affect the tube 89. The switch 92 is in series with the plate of tube 89 and the coil 14 and a som'ce of current at 89b, such as 300 volts D. C. The cam rise surface of cam 80 constitutes a large portion of its circumference during which the light-responsive system is incapable of operating the magnet M. For example, cam 00 may have a 330 dead zone and a 30 dwell which closes switch 90.

The cam 80 is connected on the crank-shaft 25 so that the dwell will close switch 90 before the armature 12 reaches the magnetic center of poles 13 during the forward stroke of the feeding device, so that the tube 89 does receive and is influenced by any impulses that may come from the photocell during the last portion of the forward feeding stroke. Cam BI is also set to close the switch 92 at the same time as or before switch 50 is closed by cam 80, and the dwell of cam 8| may and preferably does overlap the dwell period of cam 80. The purpose of switch 92 is to break the plate circuit of the tube 89 in order to prepare or reset it for the next impulse. Thus, during operation, as the feeding device approaches the end of its stroke, switches 90 and 92 are closed so as to transmit from the photocell 15 to the electromagnet M the impulse made whenever the registering index or printed matter at 93 (Figure 9) affects the photocell. As will be explained, the photocell preferably does not correct on every stroke, but relatively infrequently, such as on one in five or more strokes. Energization of the poles 13 of the magnet magnetically seizes the armature 12 which is drawn back into the space between the poles, thus swinging levers 69 on their pivots 10 and pushing the gripping members 66 forward so as to lift them off the web I l therebelow.

When this release of grip occurs, the tension drag at K restrains the web ll and causes the lower reciprocating feeding member .0 to slip under the web without forwarding it. In this fashion, the photocell terminates the forward motion of the web precisely at the time when the index or other printed matter 93 influences the photocell. The corr ction made when the p hotocell energizes the magnet '14 is determined by the distance of the magnetic center of poles '13 from the most forward position of the magnetic center of armature 12. By making this distance or "correction comparatively large with res ect to the amount of overfeed of the stroke, such as inch correction for an overfeed of 0.01, the armature comes into action only infrequently,

such as about once in three strokes in the specific instance cited. Since the cams B and 8| prevent any impulse from the photocell from affecting the electromagnet until near the end of the forward feeding stroke, any amount of intervening printed matter can be present on the web, provided it is not too close to the index or registering printed matter to which the photocell is set to respond and such intervening matter will not interrupt the feeding by releasing the grip ping member. This system is extremely practical since it allows application of the feeding, cutting and stacking system to almost any printed web since the photocell can be set to use, as the registering index on the web, any part thereof that may be desired. The index can be near the middle or near the end of the labeled sections of the continuous web into which it is to be divided. It is always possible to find on a printed label some index mark which is preceded by a clear area or vice versa depending upon whether the photocell system is to be set to register upon increase of light-reflection or transmission or decrease thereof.

The opening of the switches Q0 and 92 deenergizes the electromagnet and allows the gripping members 66 to rest upon the web but since the gripping members are inclined downwardly and forwardly, the return stroke merely causes them to slide freely over the web, whereas the forward stroke tends to increase the gripping action because of this inclination. Furthermore, clamping means is provided as described hereinbelow for holding the web in the forwardly fed position during cutting.

S troke adjustment Besides the ability of adjusting the stroke by resetting the position of pin 4'! in slot 49 (Figures 2a and 11) which can only be done when the machine is not in motion, there may be provided, as shown in Figure 11, an additional adjustment which can be made during operation of the machine. In this modification, the lever 52 is set in the downwardly extending position shown in Figure 11 when the feed plate 40 is at its foremost position, and lever 52 is connected by a link 53a to the crank rod 53?]. Link 53a and rod 531) are pivotally connected with a link 530 at 5301. Link 530 is pivotally connected at 53c to a follower 53 which has a threaded bore engaging the screw shaft 53g supported in bearings at and provided at one end with a bevel gear 5% which meshes with bevel gear 537' fixedly mounted on shaft 5370 which extends through the side of the machine and carries a handwheel 53m accessible to the operator. In the position shown with the feed plate 48 in its foremost position, the follower 53f is in intermediate position and the link 530 makes approximately a right angle to the screw 53g. Also, in this position, the center of pivot 53d is slightly above the straight line through the center of shaft 25 and the center of the pivotal connection of link 53a with lever 52. With this construction and disposition of the parts, it requires a considerable movement of follower 53f along the screw shaft 539 before an appreciable shift occurs in the forward point of the feed plate 4!! although even very small movements of the follower 53 from the position shown cause definite movement of the rearmost point of the feed plate stroke.

Tensioning means The tensioning device K comprises a smoothbottomed pan 200, the handle of which is pivotally Clamping mean This means is best shown in Figures 2a, 2b, 3a, 3b, 4 and 5 and comprises the mechanism shown in J and in N. Their operation is derived from an eccentric M on the crank-shaft 25. This eccentric works against the arm 95 of a bell-crank lever having a sleeve 95a rotatably mounted on a cross-shaft 95 and two other arms 9'? which are connected by the tie-rods 98 to levers 89 pivotally mounted on the cross-rod 6|. Springs I30 around the threaded posts IIll urge a transverse clamp bar I02 downwardly against the web and the upper surface of a cross-bar I03. Pins IE4 extend through bores in the cross-piece I63 from their upper ends which are engaged under the outer ends of the clamp bar 102 to their lower ends engaged upon the ends of the levers 99. It will be seen that when the eccentric 94, as viewed in Figure 2a, swings the arm of the bell-crank lever $5 in a counter-clockwise direction, the pins Ifld raise the clamp bar I02 and allow free passage of the web but when the eccentric 94 allows the arm to swing in a clockwise direction, the clamp bar is urged by the springs lilil' against the web.

A tie-rod I65 extends through a bore in the arm 95 and at its other end through another bore in an arm I06 of the bell-crank lever having a long sleeve Inca. (similar to 95a of the other bellcrank lever) rotatably mounted on a cross-rod Hi1 and having a pair of arms I88 through bores in the ends of which threaded tie-rods I69 extend. The threaded tie-rods I09 extend upwardly through bores in a transverse fixed plate I It and springs III thereabove urge the tie-rods upwardly by means of collars H2. The tie-rods are fixed in a transverse member H3 which has an offset upper surface adapted to form a lower clamping jaw. It cooperates with the lower surface of an upper fixed member N4, the forward edge of which is adapted to cooperate with the reciprocable knife H5.

It will be seen that when the eccentric 94 swings the arm 95 of the bell-crank lever in a counterclockwise direction and thereby releases the clamp bar I82 of the clamping means J, at the same time the tie-rod 5 t5 swings the arm I06 of the other bell-crank lever in a counterclockwise direction, and this causes the threaded tierod I09 to pull the clamp bar I I3 downwardly against the spring III to release the clamping action in the clamp N. Vice versa when the eccentric 94 swings the arm 95 in a clockwise direction, both clamps resume clamping position under the action of the springs I and III, respectively. Nuts may be provided upon the posts IOI and on the threaded tie-rods I09 to adjust the spring tension.

A pair of curved rods H6 extend from sleeves Ill which are adapted to be secured on a crossrod II8 by means of set screws H9. These rods H6 may be set further apart to accommodate a wider web, or may be shifted endwise of the rod 8 to control the path of travel of the web through the mechanism. In general, however, it is preferred to set them so as to guide the Web along a path which is centered with respect to the feeding mechanism of the machine.

a Cutting mechanism Stacking mechanism This mechanism is shown in Figures 2b, 3b, 6 and '7. It is supported by two rods I28 and I29 which extend into bearings in the end plate Id and are secured at their other ends by bolting to the upright frame plates it. It has a carriage comprising an upright plate IE8 having sleeves I3I and 632 which fit slidably on the rods I28 and I29. The upright member iSil has secured at one side of its top a vertical plate I33 which extends from the plate iSEl toward the feeding and cutting devices (see especially Fig. 32 A yoke member ES-lfits slidably on the vertical plate 533 and has a lateral extension or lug E35 adapted to receive the enlarged end. 536 of the adjusting screw i3? which engages a threaded bore in the ertica-i plate 538 but is free to rotate in the lug i355. A vertical channel-shaped member 38 is secured. by screws iii) to the yoke I3 3, and an opposite channel-shaped member Hie is secured to the end of the plate i33 along the lower portion of one side thereof. As shown best in Figures 222, and '7, a member having one or more projecting serrations H ll is provided at the bottom edge or both channels.

A lifting block i 32 mounted in the upper end of a slide member which in turn is mounted slidably in suitable guide members I53 and M5, is adapted to move upwardly to lift a cut section past the serrated edges I ii of the bottom of a stack of such sections supported between the vertical channels 538 and his. The serrations protrude so as to narrow the width between the channels because the arching of the sections as they are lifted upwardly therebetween tends to grip the ends of the hottc. cut pieces and hold the entire stack within the space between the channels even after the block is lowered.

The block i 52 is reciprocated by means of an arm Hi6 having a slot at the end thereof for receiving a pin i lf secured to the slide member M53. The arm i iil extends from a sleeve Ml which is slidable relative to a shaft I48 but secured for rotation thereby by means of a key ice. An arm its is secured to the inner end of shaft 5 58 (Figures 21) and 6) and carries at its lower end a follower it. which engages in the cam groove E52 of a rotatable cam 553 secured to the shaft 29.

As will be seen, rotation of cam :53 oscillates the lever 50 which rocks the shaft M8 and oscillates lever 5:36 which in turn imparts reciprocating motion to the block Hi2. This is timed to lift a cut section immediately after cutting by the knife iii: into the magaz ne constituted by the channels H8 and Hi).

General operation While the operation of each individual functioning mechanism has been described hereinabove, the general sequence of operation is now given in broad outline in order to facilitate a general understanding of the machine.

The web of material carrying the repeated indicia or pattern at (Fig. 9) is drawn from the rotatable reel It by the action of the withdrawing roll 36 which makes a planetary motion around the axis of shaft 28. This drawing motion from the reel takes place while the clamp I02 holds the web to prevent withdrawing the Web back out of the machine. After the drawing action of roll 36 is completed for a given cycle, the clamps J and N release the web and it is apparent that there will be slack material between the roll 38 and the reel It so that the feeding mechanism M which now enters its forward feeding stroke does not act to rotate the reel Iii. The feeding mechanism takes up only part of the slack between 33 and it during the forward stroke. The light-responsive system is present in readiness for operation near the end of the forward feeding stroke of M so that it may then receive an impulse from the change in light-reflecting or transmitting characteristics of the web caused by the passage of the predetermined index mark or pattern element 93 into the field of view of the photocell 15, which passage indicates the need for correction. Such impulse causes energization of the electromagnet 14 which maintains the grip of the feeding mechanism until the magnetic center of the armature i2 has been moved by the forward feeding stroke of the mechanism M to the magnetic center of poles 73, after which the web is released. As stated hereinbefore, the cams 89 and 8| are set so as to incapacitate the electrical system connected with the photocell except near the end of the stroke when the proper index is about to come into the field of the photocell.

At the completion of the forward feeding stroke, clamps m2 and I I3 are actuated to hold the web in position and the knife I I5 is moved upwardly to cut the protruding section of the web. Immediately following this, the block M2 lifts the cut sections past the serrated members Isl in the bottom of the magazine between the channels I38 and I48. This operation is repeated indefinitely and the operator may remove the stacked sections from the magazine at any time desired.

The machine may be employed for cutting any indexed or printed web. For example, it may be employed to out substantially uniform lengths repeatedly from a ribbon of cellophane, paper, felt, a fabric, or from a flattened tube of such material, such as regenerated cellulose sausage casings, or tubes used for forming bottle bands and the like. The webs or flattened tubes may be made of any desired material, such as cellulose derivatives, of which cellulose acetate and cellulose ethers such as ethyl cellulose and hydroxy ethyl cellulose are representative, resinous bands such as those of vinyl resins, nylon, polyethylene, proteins, such as casein, and the like. The web may contain any indicia, labels, printed designs or the like desired and any portion of each of such marks that is preceded by or followed by a relatively contrasting portion of the web may be employed. While the light-responsive system actually shown depends upon light reflected from the web, it may be employed when the web has some transparent or even translucent portions in cooperation with the light source positioned to transmit light through the web.

It is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined in the appended claims.

We claim:

1. Feed mechanism for intermittently advancing a Web of material comprising a frame, a

reciprocable member mounted on the frame for carrying the material to be fed, means for pressing the material against the reciprocable mem-- ber during its forward feeding stroke, means for reciprocating the member comprising a crank shaft, a lever oscillatable about an axis and connected to the reciprocable member for converting the oscillations of said lever into reciprocating motion of a member, a link connecting said lever with a crank rod carried by the crank shaft, an adjustable link pivotally connected to the crank rod at its pivotal connection with the firstmentioned link, and means comprising a handle accessible to the operator for adjusting the adjustable link during operation of the machine.

2. Feed mechanism as defined in claim 1 in which the first-mentioned link and crank rod are disposed approximately in a straight line and the adjustable link is disposed approximately at right angles to said straight line when the member is at the forward end of the feeding stroke.

3. Feed mechanism for intermittently advancing a web of material comprising a frame, a reciprocable member mounted on the frame, a plurality of parallel bars fixedly carried on the member and over the top of which the web is to be passed longitudinally of the bars, a supporting element fixedy secured to the member and extending above the path of the web over the bars, means for gripping the web comprising a transverse member pivotally mounted on the element on an axis transverse of the bars and of the direction of travel of the web and gravitationally urged downwardly into a position inclined somewhat from a perpendicular to the web with the lower end thereof engaging the web forwardly of the perpendicular through the pivotal axis and pressing the web against the bars, and means for reciprocating the reciprocable member, electromagnetic means mounted in fixed position on the frame, a magnetic element linked to the transverse gripping member for movement therewith and arranged to be carried thereby into the influence of the electromagnetic means at least during the last portion of the forward feeding stroke of said transverse gripping member, and a photocell disposed along the path of the web to receive light impulses therefrom, said photocell being connected to the electromagnetic means to energize said means in response to a change of light impulse.

4. Mechanism as defined in claim 3 in which the means for receiprocating the reciprocable 10 member comprises a crank shaft, a lever oscillatable about an axis and connected to the reciprocable member for converting the oscillations of said lever into reciprocating motion of the member, a link connecting said lever with a crank rod carried by the crank shaft, an adjustable link pivotally connected to the crank rod at its pivotal connection with the first-mentioned link, and means comprising a handle accessible to the operator for adjusting the adjustable link during operation of the machine.

5. Mechanism as defined in claim 3 comprising means for adjusting the stroke of said reciprocable member.

6. Mechanism as defined in claim 3 in which the electromagnetic means is an electromagnet adjustably mounted in fixed position above the transverse gripping member and the magnetic element is an armature extending upwardly from the transverse member.

7. Mechanism as defined in claim 6 in which the magnetic element is fixedly connected to the transverse gripping member and means is provided for adjusting the electromagnet along the direction of reciprocation of the transverse gripping member to set the magnetic center of the poles of the electromagnet a predetermined distance back of the most forward position of the magnetic center of the armature during reciprocation thereof.

ARTHUR O. RUSSELL. MICHAEL GRAVATT JONES. WILLIAM M. WATTS.

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